The present invention relates to a fuel injection pump which may be, but is not limited to, the distribution type and, more particularly, to an apparatus for compensating a fuel injection timing of such a pump.
Where an internal combustion engine, particularly a diesel engine, designed for use at ordinary low altitudes is operated at high altitudes as during uphill climbing of a motor vehicle, an excessive supply of fuel occurs due to the thin air and this not only deteriorates the fuel economy but causes emission of smoke resulting in environmental pollution. It is therefore necessary to compensate the fuel injection both in quantity and timing in accordance with a variation in air density originating from a change of atmospheric pressure.
A current tendency in the art of internal combustion engines is to the use of turbochargers or like superchargers for increasing the engine output power and enhancing the fuel economy. In an engine with a supercharger, the injection quantity must be adjusted to match with an amount of intake air fed to each engine cylinder by the supercharger, while the injection timing must be controlled in relation with, for example, the output and thermal load of the engine.
Heretofore, an apparatus for compensating the quantity of fuel injection has been proposed as typified by an atmospheric pressure compensator or a boost compensator. However, an apparatus capable of varying the timing of fuel injection in accordance with the atmospheric pressure or the boost pressure has been unknown to the art.